Automatic circuit breaker



Filed May 24, 1932 2 Sheets-Sheet mam/21W y 1934- w. RBULLARD 1,959,522

AUTOMATIC CIRCUIT BREAKER Filed May 24, 1932 2 Sheets-Sheet 2 WMXMI Inverz i'on Patented May 22, 1934 1 UNITED STATES PATENT OFFICE 1,959,522 AUTOMATIC CIRCUIT BREAKER William R. Bullard, Flushing, N. Y. Application May 24, 1932, Serial No. 613,311 I 7 Claims. (Cl. 175 -294) The device forming the subject matter of this generating station busses 2, through circuit application relates to control methods and mechbreakers 5, the primary distribution circuits 6, anisms for circuit breakers of a general type the distribution transformers 7, and the circuit which will be set forth more fully hereinafter, breakers 8. The circuit breakers 8 may be of when opportunity is afforded to discuss and exthe construction hereinafter described, or they plain certain figures of the drawings, and the inmay be of the automatically-reclosing type now vention has for its general object, the provision in use. of a simplified and improved controlling method, For installations such as that delineated in which will permit the use of a correspondingly Fig. 1, the type of automatic circuit breaker 1o improved and simplified mechanism, sundry difllused most widely at the present time, is the wellculties (hereinafter discussed) in existing devices known network protector. The network probeing avoided. tector has embodied in its construction a means It is within the province of the disclosure to whereby it is caused to open, should current feed improve generally, and to enhance the utility of, through it, toward the generating station busses 15 devices of that type to which the invention ap- 2; a'c'ontingency which might arise, for instance, pertains. if a short circuit should occur in one of the With the above and other objects in view, primary distribution feeders 6, or in the diswhich will be made manifest as the description tribution transformers 7. The so-called network proceeds, the invention consists in the novel conprotector is so constructed that it will reclose 20 struction and arrangement of parts hereinafter afterthe-short circuit has been remedied, and described, delineated in the drawings, and normal voltage restored to the particular feeder claimed, it being understood that an engineer 6 or transformer 7 which was responsible for or electrician, instructed by the present disclosure, the trouble. According to the existing state of and working within the scope of what is claimed, the art, the opening operation is governed by 2 can make such changes as fall within the scope a power-directional relay which, so far as the of mechanical skill, without departing from the function under discussion is concerned, has an spirit of the invention, or placing the utility established standing of long duration. To the thereof in jeopardy. aforesaid relay, certain features have been add- The accompanying description and claims will ed, by prior inventors, for the purpose of con- 0 be best understood when read in connection with trolling the reclosing operation. These addithe drawings, wherein tions have made necessary a connection of cir- Fig. 1 is a circuit diagram illustrating one incuits across the open contacts of the circuit stallation wherewith the device forming the breaker, and have, introduced complications subject matter of this application is capable of which are undesirable, when cost, ease of main- 35 use? tenance, and simplicity of operation are taken Fig. 2 is a diagram showing one form of the into consideration. Furthermore, in known deinvention; vices ,of the prior art, the opening operation of 3 i a d a ra ma ic v ew showing a slight the control relay is caused to be too sensitive modific tion in h in l in relay; as to function, when the circuit breaker shown 0 4 s a diagram ust at ng a modification. at 5 in Fig. 1 is opened, and the magnetizing cur- The device which forms the subject matter of rent of the distribution transformer 7 is supthe present application, has reference to certain plied backward through the circuit breaker 8. control methods and combinations of mechanisms This sensitivity introduces still further comp1i for automa a y reclosing Circuit a e s, more cations as to adjustments, and calls for circuits 45 especially those which are used in connection with and mechanisms of an intricate nature; all of I low volta,;e alternating net works, a typical but which has been found undesirable in many innot mand t y m of Which s Shown in Fig. 1 stances, especially in installations wherein eleva- O the drawingstors and the like derive their current from the In Fi 1, th a rs 1 a sh wn nne ted power circuits. Another disadvantage of the 50 to the generating station busses 2, by way of standard equipment is that regeneration somecircuit breakers 3. The low tension network or times is produced, the circuit breakers 8 opercircuit is marked by the reference character 4, ating when it is not desired that they should and to the same are connected the utilization do so. devices (not shown) of the users of electricity. In addition. to all of the foregoing, existing 55 current is supplied to the circuit 4, from the apparatus for the general end in view employs complicated means for operating the circuit breakers, with corresponding increase in cost and withcorresponding difliculty of maintenance.

.Having thus commented on the state of the prior art, it may be observed that the present invention relates to control methods and mechanisms for circuit breakers which function in a manner analogous to that hereinbefore described,

' the present device, however, being characterized by a simplicity which obviates the diificulties enumerated, as well as others which will suggest themselves to a person skilled in the art to which the present invention appertains. While one of the principal applications of the invention has been set forth, it will be appreciated that the invention is not limited to use in the particular system referred to. As a matter of fact, it may be employed wherever it is desired to operate two or more sources of supply in parallel, with automatic disconnection and reestablishment of the supply circuits. It will be understood also, that the methods, mechanisms, and principles which characterize the present disclosure can be applied not only to low voltage circuit breakers, but, as well, to high voltage circuit breakers, of the oil type or otherwise, and in any particular arrangement desired.

Passing now to Fig. 2, wherein theessential features of one form of the invention are shown,-

the numeral 9 designates, generally, a circuit breaker, including stationary contact terminals 10, with which the movable contact terminals 11 coact. The movable contacts 11 may, if desired, be carried by arms 12, secured to a shaft 14 journaled in bearings 15. Although a two-pole circuit breaker is shown, any number of poles may be used depending upon the munber of wires in the circuit which it is desired to control. In order to make the operation clear, a specific application of the invention is shown, and the same is similar to that disclosed in Fig. 1. Thus, the transformer 16 of Fig. 2 corresponds to one of the transformers 'l of Fig. 1. The numeral 1'? marks a power-directional relay of any approved or conventional type, a relay of the revolving disk type having been selected for the purposes of instructive illustration. The series winding of the relay 17 appears at 18, and the potential-winding at 19. The series winding 18 is-energized from the secondary winding of the current transformer 20, or in any other conventional way.

The series winding 18 and the potential winding 19 act on the disk 21, which is secured to the shaft 22, so as to rotate the shaft, and cause a member 23 carried by an arm 24 on the shaft to move to open position with respect to the contact terminals 55, shown in Fig. 2, and to close upon the contact terminals 25, in the event of a power flow in a direction from the circuit breaker 9 toward the transformer 16. It is to be understood, however, that under normal conditions, a torsion spring 26, acting on the shaft 22, tendsto turn the shaft and the disk 21 in such direction that the member 23 will be in open relation to the contacts 25. One end of the torsion spring 26 is secured to the shaft 22, and the opposite end of the spring is anchored at 27. A damping magnet 28 may be employed to retard the rotation ,of the disk 21 and the shaft 22;

although whether the damping magnet is used or omitted, is a matter of choice. The relay 17 is disclosed as a single phase relay, but a polyphase relay may be resorted to, if the circuits to be controlled are of the polyphase type. The relay 1'! preferably is somewhat insensitive to electrical impulses, to the end that the actuating power fiow must be relatively large, in order to cause it to operate.

At 29 there appears an interlocking relay, including a pivoted armature 30, carrying a flexible blade 31. The armature 30 is responsive to a holding coil 32, to move the armature to open position with respect tofcontact terminals 33, but the armature normally is held closed upon the terminals by a rectractile spring 34, the pull of the coil 32 being insuflicient to overcome the pull of the spring, when the parts are arranged as shown in Fig. 2. When, however, the armature 30 is moved mechanically toward the holding coil 32, the increased force exerted by the coil, due to its closer proximity to the armature 30, will be sufficient to hold the armature in open position with respect to the contacts 33, so long as the coil is energized.

The means for moving the armature mechanically, as aforesaid, may embody a combined armature-actuating and stop member 35, such as a rod, mounted for longitudinal reciprocation in guides 36, and provided intermediate its ends with a laterally-extended, U-shaped ofiset 37.150 The rod 35 carries an outstanding tripping finger 38, and it is this part that engages directly with the resilient blade 31 of the armature 30, to move the armature mechanically to open position with respect to the contacts 33. Longitudinal move- 105 ment is imparted to the rod 35 by solenoids 39 and 40 at the ends of the rod, these solenoids acting magnetically, directly on the rod 35 itself, or on suitable armatures (not shown) upon the rod, and well understood by those skilled in 110 the art. 1

The showing of the holding coil 32 in Fig. 2 is illustrative merely, and changes are possible, one modified structure being depicted in Fig. 3. In

that figure, parts which have been mentioned hereinbefore are designated by numerals already used, with the suffix a. The modification consists in placing spaced contacts 41 in the winding of the coil 32a, the armature 30a carrying a member 42 which bridges the contacts 41 and closes the circuit through the coil 32a, when the armature 30a is in open relation'with respect to the contacts 33a, the circuit of the coil 32a. being opened, as shown in Fig. 3, and the coil exerting no pull on the armature 30a, when the armature closes upon the contacts 33a.

Passing on to the circuit breaker mechanism, Fig. 2 shows that a shaft 43 is journaled for rota: tion in bearings 44, and is actuated by a spring motor 45 of conventional make-up. A handactuated winding mechanism 46 for the spring motor 45 is provided, but those who wish to wind up the motor 45 electrically will do so upon the bare-suggestion, and in the absence of any showing of an electrical motor in the drawings.

At one end, the shaft 43 carries a crank arm 47, and there is a crank arm 48 on the shaft 14 of the circuit breaker 9, the aforesaid arms being operatively united by a connection 49 pivoted to each of them. It willnow be understood that the spring motor 45 supplies power for opening and closing the circuit breaker 9, and it is a simple and satisfactory means for accomplishing that result. This, however, does not mean that no other mechanism for actuating the circuit breaker 9 can be used. On the end of the shaft 43 that is remote from the crank arm 47, there is a crank arm 50. The spring motor 45, or its equivalent, maintains constant torsional force on the shaft 43, in the direction of the arrow, but when the v 17, and permit the spring 26 to circuit breaker 9 is in the open position of Fig. 2, the crank arm 50 rests against the rod 35.

In practical operation, and assuming that the circuit breaker 9 is open, as shown in Fig. 2, no energy is supplied to the transformer 16 from the circuit 51, corresponding to the circuit 6 of Fig. l. The spring 26 will exert torsion on the shaft 22 of the power-directional relay 17, the member 23 being in open position with respect to the contacts 25, and in closed position with respect to the contacts 55. If, now, the transformer 16 is made alive from the circuit 51, the solenoid 39 will be energized, thereby causing the stop rod 35 to move toward that solenoid, thereby releasing the crank 50, and the shaft 43 will perform a half-revolution under the action of the spring motor 45 or its equivalent, the crank 50 passing through the offset 37 of the stop rod 35, and coming to rest against the lower portion of the stop rod in Fig. 2.

In making the aforesaid half-revolution, the shaft 43 will operate the crank arm 47, and motion will be transmitted to the shaft 14 of the circuit breaker 9, by way of the crank arm 48 and the connection 49, the arms 12 carrying the movable contacts 11 into engagement with the stationary contacts 10. This is the normal position of operation of the system. Suppose that a short circuit should occur in the transformer 16, or in the primary circuit 51. duced by the short circuit will be in such direction as to exert force on the disk 21 of the powerdirectional relay 17, rotation being imparted "to the shaft 22, the member 23 moving to open position with respect to the contacts 55, and to closed position with respect to the contacts 25. When the member 23 is in closed position upon the contacts 25, the solenoid 40 will be energized, a pull will be exerted on the stop rdd 35, and the crank 50 will be released, so that the crank can again swing through the offset 37 of the stop rod, the crank assuming again the position shown in Fig. 2, as the shaft 43 is actuated by the spring motor 45, or its equivalent. By this movement of the shaft 43, motion is transmitted by the parts 47, 49 and 48 to the shaft 14, and the circuit breaker 9 will be opened at 11-10, as shown in Fig. 2. The opening of the circuit breaker 9 will stop the power flow, remove the force acting on the disk 21 of the power-directional relay reverse the rotation of the shaft 22, the member 23 moving to open position with regard to the contacts 25, and to closed position with regard to the contacts 55.

As the stop rod 35 moves toward the solenoid coil 40, the finger 38 on the rod will engage the resilient blade 31 on the armature 30 of the interlocking relay 29, the armature being moved toward the holding coil 32, the said coil then holding the armature 30 in open position with respect to the contacts 33-, if any voltage remains on the supply circuit 51. So soon as voltage is completely removed from the supply circuit 51, the spring 34 will move the armature 30 back to its normal position, closing the contacts 33, and placing the solenoid coil 39 in condition to receive current from the transformer 16, and thereby start the reclosing action of the circuit breaker 9, so soon as energy is restored to the-supply circuit 51.

In Fig. 4, a modification of the invention is shown, in a simplified form. In this instance, the device is used to control a three phase power system. In place of the power-directional relay 17 of Fig. 2, a power-directional device of a different sort is applied directly, by mechanical Then the power flow promeans, to the latching mechanism of the circuit breaker. The operating power for the circuit breaker is obtained from a solenoid.

Referring to Fig. 4, there is shown, at 60, a circuit breaker latch, which is fulcrumed intermediate its ends at 61, and is adapted to engage a tooth 68 on the circuit breaker 69. The latch is pivoted at 62 to a. tripping rod 63, mounted for right line sliding movement. Attached to the tripping rod 63 are the potential coils 64, excited from the three phases of the supply circuit. In magnetic relation to the coils 64 are the current coils 65. The coils 65 are excited from the supply circuit through the current transformers 66, or other conventional means. The interlocking relay appears at 67, and is similar to the relay 29 of Fig. 2, save that three holding coils 77 are provided, one for each phase.

The practical operation of the form shown in Fig. 4 is as follows:

Assume that the circuit breaker 69 is in closed position. A short circuit in the supply circuit will cause a heavy current flow in one or more of the coils 65. A force will be exerted between the coils 65 and the coils 64, in such direction as to cause the rod 63 to trip the latch 60, and free it from the tooth 68 of the circuit breaker 69. A spring 70 then actuates the circuit breaker 69, closing the contacts shown at 71, and mechanically tripping the armature of the interlocking relay 67, as hereinbefore described in connection with the form shown in Fig. 2. The contacts 72 of the relay 67 will remain open until all three phases of the transformers 73 are completely deenergized, the holding coils 77 exercising the function which their name indicates. When the transformers 73 are de-energized, the spring 75 that is connected to the armature of the relay 67 will cause the armature to close the contacts 72. If, then, the transformers 73 are re-energized, the solenoid 76 will receive energy, and cause the circuit breaker 69 to close, thus completing the cycle.

The chief advantages of the invention hereinbefore set forth, over apparatus and methods at present in use, are: marked simplicity, lower cost, and freedom from difliculties of incorrect operation due to the sensitivity and complexity of devices at present in use.

Having thus described the invention, what is claimed is:

1. In combination, an electric supply, circuit, an electric load circuit, a circuit breaker for interconnecting said two circuits, a directional relay for controlling the opening and closing of said circuit breaker, a closing circuit for controlling the closing of said circuit breaker, auxiliary contacts on said directional relay for connecting said closing circuit across said supply circuit when there is no fiow of energy through said circuit breaker or when the flow of energy through said circuit breaker is in the direction from said supply circuit toward said load circuit, and an interlocking relay preventing said circuit breaker from closing until after said supply circuit has first been nearly or completely de-energized and then reenergized after said circuit breaker is opened, said interlocking relay comprising,contacts in said closing circuit operable by the operating mechanism of said circuit breaker when said circuit breaker is opened, an armature in movable relation with said contacts, and a holding coil in magnetic relation with said armature and connected across said supply circuit.

. 2. In combination, an electric supply circuit, an electric load circuit, a circuit breaker for interconnecting said two circuits, a directional tripping device for .controlling the opening of said circuit breaker when the fiow of energy through said circuit breaker is in the direction toward said supply circuit, said tripping device comprising an armature and two operating windings for each of one or more of the phases of said supply circuit, one of said two operating windings being in series relation with said circuit breaker and the other of said operating windings being connected across said supply circuit or said load circuit, a closing circuit connected across said supply circuit for controlling the closing of said circuit breaker, and an interlocking relay for preventing said circuit breaker from closing until after said supply circuithas first been nearly or completely de-energized and then re-energized after said circuit breaker is opened, said interlocking relay comprising,contacts in said closing circuit operable by the operating mechanism of said circuit breaker when said circuit breaker is opened, an armature in movable relation with said contacts, and a holding coil in magnetic relation with said armature and connected across said supply circuit.

3. In combination, an electric supply circuit, an electric load circuit, a circuit breaker for interconnecting said two circuits, a spring motor supplying power to open and close said circuit breaker, a mechanical control device which when moved to an opening position causes said spring motor to open said circuit breaker and when moved to a closing position causes said spring motor to close said circuit breaker, an opening solenoid for moving said mechanical control device into said opening position, a closing solenoid for moving said mechanical control device into said closing position, said two solenoids being connected to suitable sources of electrical supply, said source of electrical supply to said closing solenoid being said supply circuit whereby this solenoid can cause motion of said mechanical control device only when said supply circuit is energized, a directional relay having two sets of contacts, one set for controlling electrical supply to one of said two solenoids and the other set for controlling electrical supply to the other of said two solenoids, said directional relay being actuated by power flow through said circuit breaker in one direction to close one of said two sets of contacts and to open the other of said two sets of contacts and being actuated by power flow in the opposite direction through said circuit breaker to open said one of said two sets of contacts and to close said other of said two sets of contacts, and

an interlocking relay for preventing said circuitbreaker from closing until after said supply circuit has first been nearly or completely de-energized and then re-ene'rgized after said circuit breaker is opened, said interlocking relay comprising,contacts controlling the supply of electric energy to said closing solenoid and operable by said mechanical control device, an armature in movable relation with said contacts, and a holdlng coil in magnetic relation with said armature and connected across said supply circuit.

4. In combination, a circuit breaker, an electric supply circuit connected to said circuit breaker, a closing circuit for controlling the closing of said circuit breaker, and auxiliary switching means in said closing circuit for preventing the closing of said circuit breaker as long as said supply circuit remains fully energized after said circuit breaker is opened, said auxiliary switching means comprising,contacts in said closing circuit, and a holding coil connected to said supply circuit, said contacts being operated bythe operating mechanism of said circuit breaker when said circuit breaker is opened, and said contacts being controlled by said holding coil after said circuit breaker is opened.

5. In combination, a circuit breaker, an electric supply circuit connected to said circuit breaker, a closing circuit for controlling the closing of said circuit breaker, and auxiliary switching means in said closing circuit for preventing the closing of said circuit breaker until after said electric supply circuit has first been nearly or completely de-energized and then re-energizcd, said auxiliary switching means comprising-contacts in series relation with said closing circuit, an armature carrying said contacts, and a holding coil connected to said electric supply circuit, said armature being moved by the operating mechanism of said circuit breaker so as to open said contacts when said circuit breaker is opened, said contacts being held in the open position by the magnetic attraction between said holding coil and said armature as long as said electric supply circuit remains energized after said circuit breaker is opened, and said armature being moved so as to close said contacts by a spring or by gravity after said electric supply circuit is de-energized.

6. In combination, a circuit breaker, an electric supply circuit connected to said circuit breaker, a closing circuit connected across said supply circuit for causing said circuit breaker to close when said supply circuit is energized, and auxiliary switching means in said closing circuit for preventing the closing of said circuit breaker until after said supply circuit has first been nearly or completely de-energized and then re-energized after said circuit breaker is opened, said auxiliary switching means comprising-contacts controlling said closing circuit operable by the operating mechanism of said circuit breaker, an armature in movable relation with said contacts, and a holding coil in magnetic relation with said armature and connected across said supply circuit.

7. In combination, an electrical supply circuit, an electrical load circuit, a circuit breaker biased to open position for interconnecting the said two circuits, incomplete means for closing the said circuit breaker, means for restraining said circuit breaker'in closed position, an operative directional relay embodying means to complete the above said incomplete means for closing the said breaker responsive only to energy from the said electrical supply circuit, said directional relay to directly release the above said means for restraining the said circuit breaker in closed position on energy supplied only from the said electric load circuit, and supplemental means for rendering the said directional relay inoperative after it has released the said restraining means until, after such action that the said load circuit has been substantially deenergized and then reenergized.

WILLIAM R. BULLARD. 

